In order to achieve stable operation in cutting-edge semiconductor manufacturing, Nikon has developed NSR-S630D with extremely accurate overlay while maintaining throughput in various conditions resembling a real production environment. In addition, NSR-S630D has been equipped with enhanced capabilities to maintain long-term overlay stability and user interface improvement all due to our newly developed application software platform. In this paper, we describe the most recent S630D performance in various conditions similar to real productions. In a production environment, superior overlay accuracy with high dose conditions and high throughput are often required; therefore, we have performed several experiments with high dose conditions to demonstrate NSR’s thermal aberration capabilities in order to achieve world class overlay performance. Furthermore, we will introduce our new software that enables long term overlay performance.
Nikon’s new immersion scanner “NSR-S630D” has been developed to deliver enhanced product overlay and CD
uniformity while improving productivity at 10 nm half pitch node and beyond. The NSR-S630D is equipped with
various advanced technologies. Among them are the new reticle stage with encoder servo control and advanced reticle
bending mechanism, new optics with enhanced correction knobs for thermal aberration control, and advanced thermally
stable wafer stage; all of which are key components to providing the best scanner solution to meet the requirements for
10 nm half pitch node and beyond.
In this paper, we describe the NSR-630D development concept and the latest performance data at factory. One of the key
factors in improving overlay is shot distortion; in order to improve shot distortion, the NSR-S630D is equipped with a
newly developed state-of-the-art projection lens. The overall overlay improvements have been made possible not only by
minimizing lens distortion through advancements in lens manufacturing techniques, but also by reducing thermal
distortion, which is especially important in actual device production. In addition, we have also added a new function for
more effective reticle heating distortion compensation. In order to improve wafer grid performance, we newly designed a
wafer table with enhanced thermal stability. We have also further improved the reticle bending system in order to
minimize the field curvature induced by projection lens thermal aberration. The new features described above, in
addition to the matured Streamlign platform, have enabled the NSR-S630D to deliver highest accuracy and stability.
The organic silicone oil applied over the surface of a fused silica glass or Kaliumdihydrogenphosphat (KDP) nonlinear
optical crystal was changed to an inorganic glass by the photochemical oxidization using a Xe2 excimer lamp in the air.
As a result, the thin film acquired a characteristic of high power laser tolerance equivalent to quartz. Dimethylsiloxane
silicone oil was spin-coated on the surfaces of a fused silica substrate and KDP to form a film of 100-nm thickness;
which were irradiated with the Xe2
excimer lamp light (wavelength 172 nm, power density 10 mW/cm2) for 60 minutes
in oxygen atmosphere. The films were further irradiated with the Nd: YAG laser of ω (1.06 μm) or 2ω (0.503 μm), and
the laser damage test (J/cm2/10 ns) was conducted. The laser damage threshold of the photo-oxidized 100 nm thick
film formed on the fused silica substrate was 72 J/cm2 in ω and 107 J/cm2 in 2ω. On the KDP substrate, the laser
damage threshold of the thin film was 32.4J/cm2 in ω and 32.6 J/cm2 in 2ω.
An adhesive method that creates properties of heatproof, waterproof, and transparent to ultraviolet ray of 200 nm and
under in the wavelength without adhesive strain was developed by putting one silica glass to another with the silicone oil
that had been photo-oxidized by Xe2 excimer lamp. The measurement by the ZYGO interferometer showed that there
was neither adhesive strain nor bubbles, and the bonding strength of 18MPa was achieved. To compare the heat
resistance of the photo-oxidized silicone oil with that of general-purpose adhesives such as silicone rubber, water glass,
and epoxy resin, the shearing tensile strength test was conducted after exposing at high temperatures from 25 to 500 °C.
As a result, the silicone rubber adhesive exfoliated at 110 °C, and the epoxy resin adhesive, at 150 °C; however, the
photo-oxidized silicone oil had the bonding strength of 6.5MPa at 500 °C.
Using photo-excited silicone oil developed a new protective hard coating method for high power laser to present the tolerance in water. The silicone oil was spin-coated onto the surface of an optical material and then irradiated with a xenon excimer lamp in the air, which transformed the organic silicone oil into inorganic glass. This technique has enabled an optical thin film capable of transmitting ultraviolet rays of wavelengths under 200 nm and possessing the characteristics of homogeneity, high density, resistance to environmental effects and to water, anti-reflective in water, and Mohs scale value of 5.
The new, strong adhesion method has been developed for optical materials to transmit vacuum ultraviolet rays by using silicone oil. Silicone oil (dimethyl siloxane) has the main chain of siloxane bonds like quartz and the side chains of methyl group. By irradiating ultraviolet rays in oxygen atmosphere, the organic silicone oil was photo-oxidized and changed into inorganic glass. The silicone oil was poured into the thin gap between two pieces of silica glass in oxygen atmosphere and irradiated with the Xe2 excimer lamp. Consequently, the siloxane of the silicone oil was bonded with the O atoms that had been absorbed on the glass surface to form SiO2. The UV transmittance of the silicone oil was
improved by 62%, from 30% before the lamp irradiation to 92% after the 60-minute irradiation. Furthermore, the adhesive strength of the silicone oil was enhanced from 0 kgf/cm2 before the irradiation to 180 kgf/cm2 after the irradiation. The honeycomb structure board and plane mirrors were adhered with the Xe2 excimer lamplight and photo-oxidized silicone oil.
The fluorocarbon thin film and fused silica glass was bonded for an ArF laser light transmittance by using silicon oil. The chemical main structure of the silicon oil has siloxane chains as in the same structure of quartz. This new bonding method was developed with silicone oil and excimer-lamp in an oxygen atmosphere. The silicone oil was put between the fused silica glass and the fluorocarbon (FEP), and an excimer-lamp was irradiated. The silicon oil ((-O-Si(CH3)-O)n) was photo-dissociated and reacted with the oxygen adsorbed on the silica glass surface to produce a SiO2. On the other hand, the H atoms photo-dissociated from the silicon oil pulled out the F atoms of the FEP. As a result, the FEP and the silica glass were combined. The results showed that the silicon oil changed to silica glass by the excited oxygen, which improved the UV rays under 200nm transmittance.